1. Technical Field
The present invention relates to a process for permeability reduction or mobility control in a subterranean hydrocarbon-bearing formation and more particularly to such a process, wherein a foamed gel is employed as a permeability-reducing or mobility-controlling composition.
2. Description of Related Art
Foamed gels are known to have a number of oilfield applications. For example, U.S. Pat. No. 5,322,125 to Sydansk teaches a process employing a foamed gel as a permeability-reducing agent to reduce gas coning in a matrix environment of a subterranean hydrocarbon-bearing formation. The foamed gel of U.S. Pat. No. 5,322,125 comprises a crosslinked polymer gel, a foaming gas and a surfactant to induce foam formation. U.S. Pat. Nos. 4,300,634 and 4,389,320 both to Clampitt also teach the use of a foamed gel as a permeability-reducing agent in a subterranean hydrocarbon-bearing formation. Despite the prior art knowledge of foamed gels having utility in oilfield applications, a need remains for oilfield applications employing alternate foamed gels other than those known in the art that have satisfactory performance properties.
Accordingly, it is an object of the present invention to provide an alternate foamed gel that performs effectively in permeability reduction treatments. More particularly, it is an object of the present invention to provide a permeability-reducing composition that effectively reduces the permeability of a desired treatment region under a broad range of subterranean conditions. It is another object of the present invention to provide a foamed gel that effectively controls the mobility of a drive fluid during a hydrocarbon recovery operation. More particularly, it is an object of the present invention to provide a mobility-controlling composition that effectively reduces the mobility of a drive fluid under a broad range of subterranean conditions. It is still another object of the present invention to provide a permeability-reducing or mobility-controlling composition that is relatively stable under harsh formation conditions including the presence of high temperatures, crude oil, high salinity brines or high hardness brines. It is further an object of the present invention to provide such a permeability-reducing or mobility-controlling composition that is cost effective, having practical economic utility in the field.